memes

It's not a matter of "nobody should be allowed to be ultra wealthy," it's a matter of "nobody should be allowed to be unacceptably poor."

If our civilization can generate wealth at an astronomical rate, then there is no morally defensible reason for anyone to be homeless, hungry, poorly educated, lacking medical care, drinking unsafe water, worked to death, or any of a number of other baseline metrics of civilization. All of those ills exist because wealth is funneled upwards at an unbelievable rate, leading to the existence of billionaires. All of that wealth should be used to raise everyone's standard of living, rather than give a handful of people more power and luxury than ever appeared in Caligula's wet dreams.

Of course the way that you accomplish that is by an exponentially progressive taxation system, and that will... probably make it impractical to be a billionaire, but frankly I think that focusing on helping the bottom end of the economic ladder is more productive than just talking about how it should be illegal to have more than a given amount of wealth.